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The 3D combination until recently has been known by a soup of numbers and letters, because the drugs involved had yet to be named by the manufacturer, AbbVie.

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An investigational drug combination for hepatitis C virus (HCV) was highly effective in patients who also had HIV, a researcher reported.

In a multicenter, phase II/III, open-label trial, the so-called 3D combination of investigational drugs with different viral targets cleared HCV in more than 93% of co-infected patients treated for 12 weeks, according to Mark Sulkowski, MD, of Johns Hopkins University.

Data for patients treated for 24 weeks in the TURQUOISE-1 trial is still accumulating, but early numbers suggest the rate will be similar, Sulkowski reported at the International AIDS Conference here.

The 3D combination includes three "direct-acting agents," or DAAs, that target different aspects of HCV replication. It's one of a wave of new drugs and drug combinations, some approved and some still experimental, aimed at curing the virus.

Indeed, Sulkowski was the principal investigator on the PHOTON-1 study looking at another combination -- sofosbuvir (Sovaldi) and ribavirin -- published this week to coincide with the AIDS conference.

And details of a second, larger study of the same combination -- the PHOTON-2 trial -- were reported here in the same session by Jean-Michel Molina, MD, of the Saint-Louis Hospital in Paris.

Both studies herald a "potential new era of treatment for hepatitis C with regimens that are shorter, simpler, and better tolerated," commented Suman Majumdar, MD, of the Burnet Institute here, who was not involved in either trial but who moderated a press conference at which some details were presented.

The key element of the new regimens is that they do not use interferon, "which does have delivery issues as well as adverse effects," Majumdar told MedPage Today.

Indeed, until recently, standard therapy for chronic HCV was weekly injections of pegylated interferon-alfa along with oral ribavirin. Neither drug attacks the virus directly and both have unpleasant and sometimes dangerous side effects.

That began to change in 2011 with the approval of two HCV protease inhibitors, telaprevir (Incivek) and boceprevir (Victrelis).

But both of those drugs also have to be given with interferon and ribavirin, and researchers and clinicians have been waiting for effective -- and all-oral -- regimens.

The interest is especially great for patients with both HIV and HCV, who are regarded as being at greater risk for the complications of hepatitis. As well, there are important treatment-limiting toxicities and drug interactions that affect HIV medications associated with interferon.

The 3D combination until recently has been known by a soup of numbers and letters, because the drugs involved had yet to be named by the manufacturer, AbbVie.

But ABT-267, an NS5A inhibitor, is now ombitasvir and the non-nucleoside polymerase inhibitor ABT-333 is now called dasabuvir. The still-nameless third drug is ABT-450, a protease inhibitor boosted with ritonavir (Norvir).

The combination is given with ribavirin, a nonspecific drug that modifies host factors in viral infections.

In TURQUOISE-1, Sulkowski said, researchers enrolled 63 patients with both viruses and assigned 31 of them to be treated for 12 weeks and the remaining 32 to get 24 weeks of therapy with the 3D combination.

Patients had to have genotype 1 HCV, but could have Child-Pugh A cirrhosis. Their HIV treatment had to be a stable regimen including either atazanavir (Reyataz) or raltegravir (Isentress) and they had to have a plasma HIV viral load of fewer than 40 copies per milliliter.

The primary endpoint was sustained viral response -- defined as no detectable virus -- 12 weeks after the end of therapy, or SVR12, which is regarded as a cure.

Among the 31 patients treated for 12 weeks, he reported, all but one had no detectable virus at the end of treatment and all but two reached SVR12 -- or 93.5% of the cohort.

The two who did not reach SVR12 included one who withdrew consent before the end of therapy but who had undetectable virus at the time and one who relapsed 2 weeks after treatment stopped.

Not all of the 32 patients treated for 24 weeks have reached the SVR12 time point, Sulkowski said, but there have been no virologic failures among the 20 who have.

On the other hand, one patient had a virologic breakthrough during therapy, at week 16.

The patients who had relapse or breakthrough both had developed resistance mutations that were not present in their virus when they started therapy, Sulkowski reported.

But no patient stopped therapy owing to adverse events, he said. Indeed most adverse events were mild or moderate in severity and no serious treatment-emergent adverse events took place.

The PHOTON-2 trial was a sister study to the PHOTON-1 study reported earlier this week by Sulkowski and colleagues.

The main difference, Molina told MedPage Today, is that PHOTON-2 had more patients and included a wider range of HCV genotypes. It "expands and reaffirms" the results of the other study, he said.

Specifically, PHOTON-2 had 274 patients from Europe and Australia, including 112 with genotype 1, 25 with genotype 2, 106 with genotype 3, and 31 with genotype 4.

In contrast, PHOTON-1 had 223 participants from the U.S. and Puerto Rico, but included none with genotype 4.

But the efficacy results in PHOTON-2 were similar if not better -- SVR12 rates ranging from 84% to 89%, compared with 67% to 94% for PHOTON-1.

There was little effect on HIV disease or treatment, Molina reported, although four patients had transient viral increases that did not require changes in their HIV therapy.

Patients not yet on HIV therapy saw no changes in their viral load, he added.

There was a transient decrease in the number of CD4-positive T cells, consistent with known effects of ribavirin, but there was no change in the percentage of CD4 cells.

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